const gender=Symbol('gender');
const obj={
    name:'三十四',
    age:17,
    [gender]:'男'
}
console.log(obj[gender]);

// symbol不可枚举

console.log(Object.keys(obj)); // 拿到可枚举的key；
console.log(JSON.stringify(obj)); // json化可枚举属性
console.log(Object.getOwnPropertySymbols(obj)); //  拿到Symbol属性key

// 反射 Reflect 
console.log(Reflect.ownKeys(obj));  // 拿到所有属性key